Simple analog detection of turn-off delay time for IGBT junction temperature estimation

IGBT modules suffer from ageing due to thermal and power cycling. Bond wire lift-off or solder layer degradation are the known failure mechanisms. For condition monitoring, an estimation of the junction temperature during operation is necessary. For this purpose, an analog measurement board consisting of simple components is presented. The turn-off delay time is evaluated for temperature estimation. Moreover, a validation of the temperature estimation with an infrared camera is performed.